Wood filler composition



Patented Sept. 25, 1951 UNl'lEDS'lATES PATENT OFFICE I woon FILLER COMPOSITION Leo Rm, Southold, N. Y., and William T. Smith,

Rahway, N. J assignors to Interchemical Corporation, New York, N. Y., a corporation of Ohio No Drawing. Application March 20, 1948,

Serial No. 16,147

This invention relates duce a creamy homogeneous filler in which the binder is completely dissolved in the solvent diluent. The mixture is then ready to be applied to the wood. Y

The resulting diluted filler is applied by brush or inany other convenient way to the surface of the wood to be filled, and after it has been allowed to stand for a while, during which time considerable diluent evaporates and the filler coating on the wood becomes dull in appearance, it is subjected to a "padding operation which consists in rubbing the thus deposited filler with a pad for the purpose of packing the filler into the pores of the wood, and removing the excess from the surface.

In prior fillers the pigments employed have generally been silicon dioxide,'the function of which is to produce a mechanical interlocking with the wood structure, a suitable extender such as gypsum or kaolin to increase the bulk, and an appropriate porous material, such as magnesium silicate, which is well adapted to act as a bulky suspension aid for the other inerts.

In all prior fillers of the character described it has been the universal practice to employ as binder an oxidizing oil which is soluble in the solvent diluent subsequently added to the paste to prepare it for use. Linseed oil has been commonly used in this connection, as well as socalled long oil varnishes, so that when the padding" or cleaning up operations of filling the wood are carried out, the filler composition would remain soft and workable for a considerable period of time in order to permit the workmen to wipe oil the excess deposited filler from the.

surface of the wood, leaving the top surface of the wood entirely clean but with the filler thorto the art of filling pores of wood prior to the application thereto of suit- Claims. (01. 260-19)" but the setting of the filler deposited on the wood came so quickly and nonuniformly (the thinner deposits dried first and the thicker deposits dried later) that it became impossible and impractical for a workman to clean reasonably large surfaces of wood, such as are found in radio cabinets, furniture, etc., and to produce uniform results.

This practice left streaks where the filler had dried and these streaks could not be removed unless the surfaces were again wetted with a solvent, in which case the filler was pulled out of the pores. On the other hand, if the work 1 were to be cleaned without partial wetting, the

padding had to be done so quickly that very little of'the filler composition was actually padded or brushed into the pores of the wood. In addition, such quick drying binders require relatively high priced reducers or diluents, such as high boiling alcohols or esters, as against the more economical aliphatic hydrocarbons which are commonly used as thinners.

For these reasons it has been heretofore considered impractical to employ quick drying binders and the art has had to be content, all things considered, to continue the use of the relatively ing of the wood for a subsequent finish is conoughly deposited in the pores of the wood. It is cerned, but they all require a long time to dry, or to set to apoint where, for instance, a lacquer coating can be applied to the wood. Usually overnight drying is best,but four hours has been considered the minimum period to condition prior fillers to take a lacquer finish. If lacquer or other similar coatings are applied over a filler which is not sufiiciently dry or set, there is a marked tendency toward grayness of the pores and a shrinking of the filler in the pores as it continues to set under the coating, causing blisters or'pinholes in the coating. For an occasional operation, the time required for the conventional filler ,may not be critical, but wherelargeproduction is desired, the time of waiting for this type of filler to set results in a serious bottleneck and materially slows down the production output. Furthermore, the binder of conventional fillers, even if thoroughly dry, is'easily attacked by the solvents. of subsequent lacquer coatings and it is one of the difliculties well known to the trade that such fillers often pufl and swell under a lacquer coating, to shrink back finally to a point below the surface level.

One object of the present invention, which is a continuation in part of our application Serial No. 616,970, filed September 17, 1945, now abandoned, is to accomplish a satisfactory filling of the pores of the wood by means of a filler which sets in a fraction of the conventional drying time, and yet permits the mechanical filling operation to be done as easily and quickly without streaking the surface of the wood or pulling the filler out of the pores.

Another object is to provide a quick drying wood filler which does permit the use of the relatively inexpensive conventional aliphatic hydrocarbon reducers.

Our experimentation and research have resulted in the accomplishments of these objects and others by a revolutionary departure from prior practice. The invention which. we have made is based on an entirely new principle which enables us to replace the-slow drying oxidizing oil binders of prior art and to successfully employ quick drying binders in exerting a retarding effect upon the drying of them so that they are kept at a state 'of proper working consistency for at least such a length of time as is required for padding, wiping and cleaning of a relativelylarger surface area in order that the filler may be applied at once to such an area without difadsorbs or rather envelops the pigment particles and forms agglomerates with them which remain well suspended after addition of so much of the incompatible diluent as is required to reduce the filler paste to working consistency. When we app y afiller of this composition upon the wood and permit the vehicle to partly evaporate to the proper point of padding, we find that we are able to fill the pores of the wood with great ease and without stickiness or drag on the"pad" and without streaking" or premature drying and that we'are able to obtain perfectly clear wood surfaces with pores completely filled. The mechanical working ability of this filler is at least the equal of the slow drying oil types of fillers of the prior art.

The principal diillculty encountered in prior attempts to use quick dryingbinders in wood filling compositions was due to'the fact that the binders were in colloidal solution in a solvent. Upon partial evaporation of the solvent, just at the time of padding, the filler became sticky and unworkable. In adding a non-solvent to the binder solution, the resin exists, after partial evaporation of the vehicle at the time of padding, in a friable, flocculent and non-sticky form which lends itself well to be packed into the pores of the wood without pull-out or drag on the pad.

Having succeeded in preparing a usable wood filler in the indicated manner, it seemed reasonable to try preparing an equally useful filler composition by what appeared to be a more practical way, namely, reducing the resin first to minute particle size by any suitable means and dispersing it then in the non-solvent without the presence of a solvent for the resin. However, a

usable filler composition could not be prepared in this manner. It appears that not all of the resin is thrown out of solutionupon the addition of non-solvent to the pigmented resin solution in amounts as herein disclosed. Some of the resin remains in solution and by virtue thereof, acts as a self-plasticizer for the precipitated portion of the resin and as such performs several vital functions; first,- it aids in the formation of the ing the binder and pigments to collect at the bottom of the solution,

By means of this principle we have been able to introduce extremely quick drying binders at low costs and to ameliorate to a great extent the dimculties and disadvantages which have been previously described.

For the filler composition of this invention we may embody the appropriate inert solid filler particles which have been heretofore employed,

such as silicon dioxide, kaolin, and magnesium silicate. In connection therewith we use binders in solvent solution, which are thrown out of solution in the above described manner when a volatile, incompatible solvent is added to the binder solution with the pigments evenly dispersed therein. In general, any water-insoluble, quick drying material may be used as the binder, provided it is soluble in an easily volatilized solvent and separates'from the solvent solution upon addition of another, incompatible solvent. We have had excellent results when employing certain natural resins, such as shellac and gum accroides, or various synthetic resins, such as oil modified phenol-formaldehyde resins, saturated oil fatty acid-modified glycerol phthalates. or the conjoint polymerization products of a drying oil acid modified alkyd with styrene, and others.

The diluent used in connection with binders of the character described must be one which is at least partially non-compatible with the dissolved binder so that part thereof is thrown out of solution upon addition of the diluent and formsthe aforesaid fiocculents. For this we have used mineral spirits with highly. satisfactory results. Other suitable diluents or combinations of diluents may also be used, such as a combination of mineral spirits, viz., aliphatic hydrocarbons, with an aromatichydrocarbon.

Hydrogenated and/or aromaticized aliphatic sol vents may also be employed as the diluent but, obviously, they must be at least partially incompatible with the binder resin.

The mixture of the filler paste and the diluent should be of'creamy consistency, having substantially the same appearance as prior conventional fillers when ready for use. This consistency may be obtained through the use of approximately one part by volume of paste to one and one-quarter parts by volume of thinner, which, in the average, corresponds to 8.25 parts by weight of thinner to -141 parts by weight of filler paste, providing a composition, ready for use, of about 11 lbs. per gallon. In the filler, the amount of binder used may correspond to conventional proportions between inert solid particles b nder it sodesired. but it is one of our amazes outstanding advantages that the amount of binder may be greatly reduced without impairingthe results. Therefore, in practicing our invention we keep the binder ratio very low, down to about one-half of the conventional.

When applied to the wood by brush or other.-

wise, thefiller composition settles readily in the pores and, since it does not form a tenacious coating or layer, any excess thereof may easily be removed from the surface. After standing at room temperature for a period substantially the same as usual for conventional filler treatment, the filler composition will assume the mealy consistency and appearance of conventional fillers at that stage. By this time, the agglomerates may be packed firmly into the pores of the Wood by a "padding operation which cuts the filler. level with the wood surface. Inasmuch as these fillers set or harden suiliciently to permit a subsequent coating with lacquers and the like without difiiculties in but a fraction of the time required for the drying of the conventional drying oil or long oil alkyd base fillers, the present invention aids 'materially in manufacturing output and elimi- As it is desirable in the filling of wood for most wood gives the desired color match. In gilsonite we found a material especially valuable for this purpose. Y

It will be apparent from the foregoing that this invention is not restricted to specific. ingredients. However, the following paste formulations are illustrative:

' Example I Into 20 lbs. of a xylol solution containing 35 per cent of the conjoint polymerization product of 4.5 lbs. of adrying oil acid modified alkyd resin (38% phthalic anhydride, 22% glycerol, unsaturated oil fatty acids) and 2.5 lbs. of monomeric styrene, and having a Gardner reading D,

there is thoroughly mixed:

41 lbs. 8 oz.. 11 lbs. 8 oz. 13 lbs.

3 lbs. 8 oz. 4 lbs.

silicon dioxide kaolin magnesium silicate raw umber Y of an 82% solution of gilsonite in mineral spirits I bone black mineral spirits 100 lbs.

In order to attain the proper consistency for application, the filler paste of the above and the subsequent examples is to be cut, with mineral spirits or any other suitable volatile non-solvent for the resin as diluent, in case of mineral spirits, preferably as a ratio of one part by volume of the paste to not more than one and one-quarter parts by volume of the thinner.

Example II- To a solution of 7.35 lbs. of a saturated fattyacid modified glycerol phthalate (phthalic anhydride 46%, glycerol 28%, stearic and cocoa nut oil fatty acids 13% each) dissolved in 13.65 lbs. xylol, there is added, while agitating:

41 lbs. 8 oz. silicon dioxide 11 lbs. 8 oz. kaolin 13 lbs. 5 oz. magnesium silicate 3 'lbs. 8 oz. raw umber 3 lbs. 8 oz. oi an 82% solution of gilsonite in mineral spirits 9 /2 voz. bone black 5 lbs. 1 oz. mineral spirits 100 lbs.

Example III Into 20 lbs. of the 35% xylol solution of the conjoint polymer of styrene-drying oil modified alkyd resin of Example I, there is mixed:

To a solution of 9 lbs. gum accroides, dissolved in 11 lbs. ethyl alcohol, there is added, while x a 41 lbs. silicon dioxide 12 lbs. kaolin v 14 lbs. magnesium silicate 7 lbs. burnt umber or Van Dyk brown 6 lbs. toluol 100 lbs. paste Example V To 20 lbs. of a' toluol solution of a tung oil modified phenolic resin of the heat reactive type, made by heating the condensation product of about two mols of phenol and one mol of formaldehyde with tung oil at a weight ratio of about one to one, there is added, under agitation:

41 lbs. silicon dioxide 12 lbs. kaolin 14 lbs. magnesium silicate 7 lbs. burnt umber 6 lbs. mineral spirits 100 lbs. paste Due to the nature and purpose of the herein exemplified compositions, quantitative changes of constituents are permissible within a considerable range. We obtain useful filler pastes having from 7 to 12 parts binder resin. While 7 parts appear to be the practical minimum to obtain a proper sealing of the pores of the wood, the workability of the filler isadversely affected if the pastecontains more than 12 parts of the binder.

The ratio of inert pigments is preferably kept at 55-68 parts. We like to add them in such proportions that about four-sixths of the total pigments is silicon dioxide while kaolin and magnesium silicate roughly represent one-sixth each.

The addition of more than '7 parts of gilsonite causes stickiness. At a ratio of 2 to 4 parts, gilsonite aids materially in darkening the pores, while 4 to 7 parts specifically tend to brighten the yellow undertone of the wood.

It is obvious that other changes may be made guesses 1. A composition according to claim 10, in

which theresin is the conjoint polymerization product of 4.5 parts of a 40% drying oil acid modified alkyd and 2.5 parts monomeric styrene.

2. A composition according to claim 1, in which the solvent for the resinis xylol and the nonsolvent for the resin is mineral spirits.

3. A composition according to claim 2, which comprises about 13 parts by weight of xylol and about 7.5 parts by weight of mineral spirits per '7 parts by weight of the resin.

4. A composition according to claim' 3 comprising about 65 parts by weight of wood filler pigments per 7 parts by weight of resin.

5. A composition according to claim 10, in

. which the resin is a modified alkyd, prepared from 28 parts glycerol, 46 parts phthalic anhydride and 13 parts of each stearic acid and cocoanut oil fatty acids, and in which the volatile organic solvent for the resin is xylol and the volatile organic non-solvent for the resin is mineral spirits.

6. A composition according to claim 5, comprising about 65 parts by weight of wood filler pigments, 21 parts by weight of a. 35% solution in xylol of the resin and about parts by weight of mineral spirits.

7. A composition according to claim 10, comprising agglomerates of 41 parts, by weight 8 solvent for the resin, phase consisting oi aggregatesbetween pigments. theremainingportionoftheresinandpartot the said solvent for the resin.

' 9. A wood illler composition characterized by having a binder constituent taken from the group or natural resins, oil modified phenol formaldehyde resins, saturated oil fatty acid modifled glycerol phthalates and conjoint polymerization products of a drying oil acid-modified alkyd with styrene, ous phase consistingv of one portion of '1 to 12 parts oi. the resin dissolved in a mixture of a volatile organicsolvent for the resin and a volatile organic non-solvent for the resin, and a flocculently' dispersed phase consisting of aggregates between 55 to 68 parts oi pigments, the remaining portion of the resin and part of the said solvent for the resin.

10. A wood filler composition characterized by ,having a binder constituent taken from the group of natural resins, oil modified phenol formaldehyde resins. saturated oil fatty acid-modified glycerol phthalates and conjoint polymerization products of a drying oil acid-modified alkyd with styrene,- said composition comprising a continuous phase consisting of one portion of 7 to 12 parts of the resin dissolved in a mixture oi. a volatile organic solvent for the. resin and a volaso tile organic non-solvent for the resin, and a flocsilicon dioxide, 12 parts by weight kaolin, and

14 parts by weight magnesium silicatewith 9 parts per weight gum accroides, dispersed in a mixture of 11 parts by weight ethyl alcohol, and 6 parts by weight toluol.-

8. A wood filler composition characterized by having a binder constituent taken from the group of natural resins, oil modified phenol formaldehyde resins, saturated oil fatty acid-modified glycerol phthalates and conjoint polymerization products of a drying oil acid-modified alkyd with styrene-said composition comprising a continuous phase consisting of one portion of the resin 5 dissolved in a mixture of a volatile organic solvent for the resin and a volatile organic nonculently dispersed phase consisting of aggregates between to 68 parts of pigments consisting to about four-sixths of silicon dioxide and to about one-sixth of each kaolin and magnesium sflicate,

35 the remaining portion of the resin and part of the said solvent for the resin.

' LEO ROON.

v WILLIAM '1'. SMITH. REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS 2,348,619 Green et al. May. 9, 1944 and a mamas said compositioncomprising acontinu 

8. A WOOD FILLER COMPOSITION CHARACTERIZED BY HAVING A BINDER CONSTITUENT TAKEN FROM THE GROUP OF NATURAL RESINS, OIL MODIFIED PHENOL FORMALDEHYDE RESINS, SATURATED OIL FATTY ACID-MODIFIED GLYCEROL PHTHALATES AND CONJOINT POLYMERIZATION PRODUCTS OF A DRYING OIL ACID-MODIFIED ALKYD WITH STYRENE, SAID COMPOSITION COMPRISING A CONTINUOUS PHASE CONSISTING OFONE PORTION OF THE RESIN DISSOLVED IN A MIXTURE OF A VOLATILE ORGANIC SOLVENT FOR THE RESIN AND A VOLATILE ORGANIC NONSOLVENT FOR THE RESIN, AND A FLOCCULENTLY DISPERSED PHASE CONSISTING OF AGGREGATES BETWEEN PIGMENTS, THE REMAINING PORTION OF THE RESIN AND PART OF THE SAID SOLVENT FOR THE RESIN. 